Conventionally, plotter devices (moving body display devices) that can store specific locations, such as harbors, gas stations, and locations where people caught a lot of fish, and display marks indicating these specific locations along with a ship position (position of a moving body) are known. For example, JP H05-288562(A) discloses this kind of plotter device.
Meanwhile, another kind of plotter device has a function to create a route from a starting point to a destination, and display the route on a screen along with a ship position. On the route, course-change points are set as locations where the ship changes the course. Typically, the course-change points are set so that the starting point connects with the destination, considering areas (including shallow water, a no-trespassing area, an island, a peninsula) which must be avoided on navigation. A method of creating the route may include storing points (positions) through which the ship passed as marks, and creating the route based on these marks. Further, another method may include setting marks which are set in advance by an operator to the starting point, stopover location(s), destination and the like, and creating the route by connecting these marks.
The method of automatically creating the route based on the points through which the ship passed is useful because the route actually taken by the ship can be reproduced. However, because the points through which the ship passed are set at a fixed interval by distance, time or the like, the course-change points are not necessarily set as the locations where the ship actually changed the course.
Meanwhile, as a method of improving the reproducibility of the route where the ship traveled in the past, the interval at which the marked positions are set may be shortened. However, if the interval at which the marked positions are set is shortened, the number of the marks to be set increases more than needed and, thus, the display screen may be visually degraded. If the number of the marks to be stored is increased, the storage area of the memory will be occupied more and a load of display processing and the like will be increased. For this reason, a method of manually setting the marks as the course-change points while the ship is changing the course may be considered. However, carrying out the operation of setting the marks whenever the ship changes the course requires a lot of time and effort, and the operator may forget the input operation of the marks just because he/she has to concentrate on navigation.
This can also be said for the input operation of the mark when storing a position where a comparatively large-sized fish such as a spearfish is caught as a fishing point. When one has a bite of the large-sized fish, in order to ensure the fish bite on the hook (hookup) or the like, a speed of the ship is desired to be rapidly increased immediately after the fish bite. However, under such a tense situation where the rapid ship handling is required, it is difficult for the operator to set the mark manually, while performing the operation of increasing the ship speed. Further, even if the operator tries to input the mark as the point where the fish bite occurs after the large-sized fish is caught or after the fish escaped, the ship has already moved away from the actual fish bite position at that time point in many cases. Therefore, it is difficult to accurately store the position where the fish bite occurs as the mark.